fix futex

[lttv.git] / usertrace-fast / ltt-usertrace-fast.c

diff --git a/usertrace-fast/ltt-usertrace-fast.c b/usertrace-fast/ltt-usertrace-fast.c
index 159c00df9f8a83752bda37204765b758a1a3a97a..d722460b10e1f4a98d4048feed7e46ea57b408c2 100644 (file)
--- a/usertrace-fast/ltt-usertrace-fast.c
+++ b/usertrace-fast/ltt-usertrace-fast.c
@@ -319,14 +319,14 @@ static inline int ltt_buffer_put(struct ltt_buf *ltt_buf,
                 * It can also happen if this is a buffer we never got. */
                return -EIO;
        } else {
-               if(atomic_read(&ltt_buf->full) == 1) {
+               if(atomic_inc_return(&ltt_buf->writer_futex) <= 0) {
+                       atomic_set(&ltt_buf->writer_futex, 1);
                        /* tell the client that buffer is now unfull */
-                       ret = futex((unsigned long)&ltt_buf->full,
+                       ret = futex((unsigned long)&ltt_buf->writer_futex,
                                        FUTEX_WAKE, 1, 0, 0, 0);
                        if(ret != 1) {
                                dbg_printf("LTT warning : race condition : writer not waiting or too many writers\n");
                        }
-                       atomic_set(&ltt_buf->full, 0);
                }
        }
 }
@@ -382,8 +382,7 @@ static void ltt_usertrace_fast_daemon(struct ltt_trace_info *shared_trace_info,
 {
        struct sigaction act;
        int ret;
-       int fd_fac;
-       int fd_cpu;
+       int fd_process;
        char outfile_name[PATH_MAX];
        char identifier_name[PATH_MAX];
 
@@ -434,12 +433,20 @@ static void ltt_usertrace_fast_daemon(struct ltt_trace_info *shared_trace_info,
        }
        snprintf(identifier_name, PATH_MAX-1,   "%lu.%lu.%llu",
                        traced_tid, traced_pid, get_cycles());
-       snprintf(outfile_name, PATH_MAX-1,      "facilities-%s", identifier_name);
-       fd_fac = creat(outfile_name, 0644);
-
-       snprintf(outfile_name, PATH_MAX-1,      "cpu-%s", identifier_name);
-       fd_cpu = creat(outfile_name, 0644);
-       
+       snprintf(outfile_name, PATH_MAX-1,      "process-%s", identifier_name);
+#ifndef LTT_NULL_OUTPUT_TEST
+       fd_process = creat(outfile_name, 0644);
+#else
+       /* NULL test */
+       ret = symlink("/dev/null", outfile_name);
+       if(ret < 0) {
+               perror("error in symlink");
+       }
+       fd_process = open(outfile_name, O_WRONLY);
+       if(fd_process < 0) {
+               perror("Error in open");
+       }
+#endif //LTT_NULL_OUTPUT_TEST
        
        while(1) {
                pause();
@@ -448,11 +455,7 @@ static void ltt_usertrace_fast_daemon(struct ltt_trace_info *shared_trace_info,
                dbg_printf("LTT Doing a buffer switch read. pid is : %lu\n", getpid());
        
                do {
-                       ret = read_subbuffer(&shared_trace_info->channel.cpu, fd_cpu);
-               } while(ret == 0);
-
-               do {
-                       ret = read_subbuffer(&shared_trace_info->channel.facilities, fd_fac);
+                       ret = read_subbuffer(&shared_trace_info->channel.process, fd_process);
                } while(ret == 0);
        }
 
@@ -460,19 +463,13 @@ static void ltt_usertrace_fast_daemon(struct ltt_trace_info *shared_trace_info,
 
        /* Buffer force switch (flush). Using FLUSH instead of ACTIVE because we know
         * there is no writer. */
-       flush_buffer(&shared_trace_info->channel.cpu, FORCE_FLUSH);
+       flush_buffer(&shared_trace_info->channel.process, FORCE_FLUSH);
        do {
-               ret = read_subbuffer(&shared_trace_info->channel.cpu, fd_cpu);
+               ret = read_subbuffer(&shared_trace_info->channel.process, fd_process);
        } while(ret == 0);
 
 
-       flush_buffer(&shared_trace_info->channel.facilities, FORCE_FLUSH);
-       do {
-               ret = read_subbuffer(&shared_trace_info->channel.facilities, fd_fac);
-       } while(ret == 0);
-
-       close(fd_fac);
-       close(fd_cpu);
+       close(fd_process);
        
        munmap(shared_trace_info, sizeof(*shared_trace_info));
        
@@ -502,25 +499,16 @@ void ltt_rw_init(void)
        shared_trace_info->filter=0;
        shared_trace_info->daemon_id=0;
        shared_trace_info->nesting=0;
-       memset(&shared_trace_info->channel.facilities, 0,
-                       sizeof(shared_trace_info->channel.facilities));
-       memset(&shared_trace_info->channel.cpu, 0,
-                       sizeof(shared_trace_info->channel.cpu));
+       memset(&shared_trace_info->channel.process, 0,
+                       sizeof(shared_trace_info->channel.process));
        /* Tricky semaphore : is in a shared memory space, so it's ok for a fast
         * mutex (futex). */
-       atomic_set(&shared_trace_info->channel.facilities.full, 0);
-       shared_trace_info->channel.facilities.alloc_size = LTT_BUF_SIZE_FACILITIES;
-       shared_trace_info->channel.facilities.subbuf_size = LTT_SUBBUF_SIZE_FACILITIES;
-       shared_trace_info->channel.facilities.start =
-               shared_trace_info->channel.facilities_buf;
-       ltt_buffer_begin_callback(&shared_trace_info->channel.facilities,
-                       ltt_get_timestamp(), 0);
-
-       atomic_set(&shared_trace_info->channel.cpu.full, 0);
-       shared_trace_info->channel.cpu.alloc_size = LTT_BUF_SIZE_CPU;
-       shared_trace_info->channel.cpu.subbuf_size = LTT_SUBBUF_SIZE_CPU;
-       shared_trace_info->channel.cpu.start = shared_trace_info->channel.cpu_buf;
-       ltt_buffer_begin_callback(&shared_trace_info->channel.cpu,
+       atomic_set(&shared_trace_info->channel.process.writer_futex, LTT_N_SUBBUFS);
+       shared_trace_info->channel.process.alloc_size = LTT_BUF_SIZE_PROCESS;
+       shared_trace_info->channel.process.subbuf_size = LTT_SUBBUF_SIZE_PROCESS;
+       shared_trace_info->channel.process.start =
+                                               shared_trace_info->channel.process_buf;
+       ltt_buffer_begin_callback(&shared_trace_info->channel.process,
                        ltt_get_timestamp(), 0);
        
        shared_trace_info->init = 1;
@@ -553,10 +541,12 @@ void ltt_rw_init(void)
                /* Child */
                role = LTT_ROLE_READER;
                sid = setsid();
-               ret = nice(1);
-               if(ret < 0) {
-                       perror("Error in nice");
-               }
+               //Not a good idea to renice, unless futex wait eventually implement
+               //priority inheritence.
+               //ret = nice(1);
+               //if(ret < 0) {
+               //      perror("Error in nice");
+               //}
                if(sid < 0) {
                        perror("Error setting sid");
                }